Electric-hydraulic power unit

Abstract

The present invention is directed to an electric-hydraulic power unit. In one illustrative embodiment, the power unit comprises a body having a movable pressure barrier positioned therein, the movable pressure barrier defining first and second chambers therein, a configurable flow path in fluid communication with the first and second chambers, and at least one valve for configuring the flow path in a first state wherein fluid may flow within the flow path only in a direction from the first chamber toward the second chamber, and a second state wherein fluid within the flow path may flow in both directions between the first and second chambers.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a hydraulic power unit (HPU). More specifically, the present invention relates to an electrically powered HPU having a hydraulically operated failsafe mechanism. In one illustrative embodiment, the present invention is directed to a subsea HPU. [0003] 2. Description of the Related Art [0004] A typical subsea wellhead control system, shown schematically in FIG. 1, includes a subsea tree 40 and tubing hanger 50. A high-pressure hydraulic line 26 runs downhole to a surface-controlled subsea safety valve (SCSSV) actuator 46, which actuates an SCSSV. A subsea control module (SCM) 10 is disposed on or near the tree 40. The SCM includes an electrical controller 12, which communicates with a rig or vessel at the surface 32 via electrical umbilical 30. [0005] Through control line 22, the controller 12 controls a solenoid valve 20, which in turn controls the flow of high-pressure hydraulic flu...

AI Technical Summary

Benefits of technology

The present invention is an electric-hydraulic power unit that includes a body with a movable pressure barrier positioned therein. The movable pressure barrier defines chambers within the body and a configurable flow path in fluid communication with the chambers. The device also includes a valve for configuring the flow path in a first state where fluid may flow in only one direction and a second state where fluid may flow in both directions between the chambers. The device can also be powered by an electric motor and can be used to control the pressure in the chambers. The technical effects of the invention include the ability to control fluid flow in both directions, and the ability to adjust the pressure in the chambers through the use of a valve.

Problems solved by technology

Typically, solenoid valves such as 20 are relatively large, complex, and expensive devices.

Each such valve may include ten or more extremely small-bore check valves, which are easily damaged or clogged with debris.

However, in the system of FIG. 2, high and low-pressure hydraulic fluid is provided by independent subsea-deployed pumping systems.

However, SCSSV's are required equipment in many locations, and thus cannot be omitted from all systems.

Also, because of the harsh downhole environment, it is not practical to replace the hydraulic SCSSV actuators with less robust electric actuators.

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